The present invention relates to a beam steering antenna unit suitable for a vehicle loaded antenna unit to be loaded for example on an automobile.
FIG. 18 shows a drawing showing the constitution of the windowpane antenna unit 200 for automobile, which is one of the conventional vehicle loaded antennas. In FIG. 18, there are provided, for example, two antenna elements 201, 202 with zigzag arrangements of a copper strip line on the rear windowpane G of automobile. These two antenna elements 201, 202 are the antenna elements which can receive the electric waves in the frequency ranges adaptable to the receiving tuner 203 for FM band (frequency modulation band), AM band (amplitude modulation band), and TV band. These antenna elements 201, 202 are selectively connectable to an FM/AM, TV tuner 203.
Thus, this windowpane antenna unit 200 for automobile is made ready to connect optionally the antenna element necessary for the related receiving tuner, and to receive the data coming in from any direction under nearly same conditions.
The conventional windowpane antenna unit 200 for automobile as described above had the following problems. Though it is usable by selectively connecting the two antenna elements 201, 202, these two antenna elements 201, 202 are provided respectively severally, and their directivity cannot be changed in the unit of the single antenna element. Accordingly, although the above conventional antenna unit is usable for receiving under nearly the same conditions without respect to the direction of the incoming electric wave (non-directivity receiving), it has a drawback of receiving the reflected waves from buildings and the like when the automobile is running in the urban street surrounded by tall buildings or mountainous area. In other words, it has a disadvantage of being susceptible to obstruction by multipass interference.